Engines, and particularly gas turbine engines, are used to power aircraft, watercraft, power generators and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses aft drawn into the engine and delivers high pressure aft to the combustor. The combustor is a component or area of a gas turbine engine where combustion takes place, hi a gas turbine engine, the combustor receives high pressure air and adds fuel to the air which is burned to produce hot, high-pressure gas. After burning the fuel, the hot, high-pressure gas is passed from the combustor to the turbine. The turbine extracts work from the hot, high-pressure gas to drive the compressor and residual energy is used for propulsion or sometimes to drive an output shaft.
Turbines typically include static vanes that redirect hot, high-pressure air moving from the combustor through the turbine and rotating blades that extract mechanical energy from the hot, high pressure air. Cooling airflow is often used to prevent vane fatigue from the heat applied to the vanes by the hot, high pressure air. Not only do the vanes themselves become hot, but the cavities forward and aft the rotor support that contain the turbine wheel are required to be maintained below a particular temperature. By circulating cooling airflow through the interior of the vane, the air may be purged into the rotor/stator cavities to cool multiple components in the system.
Typical aft circulation in a vane occurs via an impingement tube design that results in aftward flow on the inside of the vane, exiting the trailing edge of a vane. This does not lend itself to using the vane cooling air to purge rotor/stator cavities below the vane as any air purged at the leading edge has not done any cooling on the vane prior to exiting into the cavity. Moreover, designs incorporating turbulator ribs in the vane may provide too much cooling to the vane prior to the air being purged, so that the purged air is too warm to adequately cool the rotor/stator cavities.
Accordingly, new techniques and configurations are needed to tailor the temperature of cooling fluid passed through vanes into rotor/stator cavities experiencing high-temperature environments.